.\"-
.\" Copyright (c) 1990, 1993, 1994
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" the Institute of Electrical and Electronics Engineers, Inc.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"     @(#)stty.1	8.4 (Berkeley) 4/18/94
.\" $FreeBSD$
.\"
.Dd October 20, 2018
.Dt STTY 1
.Os
.Sh NAME
.Nm stty
.Nd set the options for a terminal device interface
.Sh SYNOPSIS
.Nm
.Op Fl a | e | g
.Op Fl f Ar file
.Op Ar arguments
.Sh DESCRIPTION
The
.Nm
utility sets or reports on terminal
characteristics for the device that is its standard input.
If no options or arguments are specified, it reports the settings of a subset
of characteristics as well as additional ones if they differ from their
default values.
Otherwise it modifies
the terminal state according to the specified arguments.
Some combinations of arguments are mutually
exclusive on some terminal types.
.Pp
The following options are available:
.Bl -tag -width indent
.It Fl a
Display all the current settings for the terminal to standard output
as per
.St -p1003.2 .
.It Fl e
Display all the current settings for the terminal to standard output
in the traditional
.Bx
``all'' and ``everything'' formats.
.It Fl f
Open and use the terminal named by
.Ar file
rather than using standard input.
The file is opened
using the
.Dv O_NONBLOCK
flag of
.Fn open ,
making it possible to
set or display settings on a terminal that might otherwise
block on the open.
.It Fl g
Display all the current settings for the terminal to standard output
in a form that may be used as an argument to a subsequent invocation of
.Nm
to restore the current terminal state as per
.St -p1003.2 .
.El
.Pp
The following arguments are available to set the terminal
characteristics:
.Ss Control Modes:
Control mode flags affect hardware characteristics associated with the
terminal.
This corresponds to the c_cflag in the termios structure.
.Bl -tag -width Fl
.It Ar number
Set terminal baud rate to the number given, if possible.
If the baud rate is set to zero,
modem control is no longer asserted.
.It Cm clocal Pq Fl clocal
Assume a line without (with) modem control.
.It Cm cread Pq Fl cread
Enable (disable) the receiver.
.It Cm crtscts Pq Fl crtscts
Enable (disable) RTS/CTS flow control.
.\" .It Cm rtsdtr Pq Fl -rtsdtr
.\" Enable (disable) asserting RTS/DTR on open.
.It Cm cs5 cs6 cs7 cs8
Select character size, if possible.
.It Cm cstopb Pq Fl cstopb
Use two (one) stop bits per character.
.It Cm hup Pq Fl hup
Same as
.Cm hupcl
.Pq Fl hupcl .
.It Cm hupcl Pq Fl hupcl
Stop asserting modem control
(do not stop asserting modem control) on last close.
.It Cm ispeed Ar number
Set terminal input baud rate to the number given, if possible.
If the input baud rate is set to zero,
the input baud rate is set to the value of the output baud rate.
.It Cm ospeed Ar number
Set terminal output baud rate to the number given, if possible.
If the output baud rate is set to zero,
modem control is no longer asserted.
.It Cm parenb Pq Fl parenb
Enable (disable) parity generation and detection.
.It Cm parodd Pq Fl parodd
Select odd (even) parity.
.It Cm speed Ar number
This sets both
.Cm ispeed
and
.Cm ospeed
to
.Ar number .
.El
.Ss Input Modes:
This corresponds to the c_iflag in the termios structure.
.Bl -tag -width Fl
.It Cm brkint Pq Fl brkint
Signal (do not signal)
.Dv INTR
on
break.
.It Cm icrnl Pq Fl icrnl
Map (do not map)
.Dv CR
to
.Dv NL
on input.
.It Cm ignbrk Pq Fl ignbrk
Ignore (do not ignore) break on input.
.It Cm igncr Pq Fl igncr
Ignore (do not ignore)
.Dv CR
on input.
.It Cm ignpar Pq Fl ignpar
Ignore (do not ignore) characters with parity errors.
.It Cm imaxbel Pq Fl imaxbel
The system imposes a limit of
.Dv MAX_INPUT
(currently 255) characters in the input queue.
If
.Cm imaxbel
is set and the input queue limit has been reached,
subsequent input causes the system to send an ASCII BEL
character to the output queue (the terminal beeps at you).
Otherwise,
if
.Cm imaxbel
is unset and the input queue is full, the next input character causes
the entire input and output queues to be discarded.
.It Cm inlcr Pq Fl inlcr
Map (do not map)
.Dv NL
to
.Dv CR
on input.
.It Cm inpck Pq Fl inpck
Enable (disable) input parity checking.
.It Cm istrip Pq Fl istrip
Strip (do not strip) input characters to seven bits.
.It Cm iutf8 Pq Fl iutf8
Assume input characters are UTF-8 encoded.
.It Cm ixany Pq Fl ixany
Allow any character (allow only
.Dv START )
to restart output.
.It Cm ixoff Pq Fl ixoff
Request that the system send (not send)
.Dv START/STOP
characters when the input queue is nearly empty/full.
.It Cm ixon Pq Fl ixon
Enable (disable)
.Dv START/STOP
output control.
Output from the system is stopped when the system receives
.Dv STOP
and started when the system receives
.Dv START ,
or if
.Cm ixany
is set, any character restarts output.
.It Cm parmrk Pq Fl parmrk
Mark (do not mark) characters with parity errors.
.El
.Ss Output Modes:
This corresponds to the c_oflag of the termios structure.
.Bl -tag -width Fl
.It Cm bs0 bs1
Select the style of delay for backspaces (e.g., set BSDLY to BS0).
.It Cm cr0 cr1 cr2 cr3
Select the style of delay for carriage returns (e.g., set CRDLY to CR0).
.It Cm ff0 ff1
Select the style of delay for form feeds (e.g., set FFDLY to FF0).
.It Cm nl0 nl1
Select the style of delay for newlines (e.g., set NLDLY to NL0).
.It Cm ocrnl Pq Fl ocrnl
Map (do not map) carriage return to newline on output.
.It Cm ofdel Pq Fl odell
Use DELs (NULs) as fill characters.
.It Cm ofill Pq Fl ofill
Use fill characters (use timing) for delays.
.It Cm onlcr Pq Fl onlcr
Map (do not map)
.Dv NL
to
.Dv CR-NL
on output.
.It Cm onlret Pq Fl onlret
On the terminal, NL performs (does not perform) the CR function.
.It Cm onocr Pq Fl onocr
Do not (do) output CRs at column zero.
.It Cm opost Pq Fl opost
Post-process output (do not post-process output;
ignore all other output modes).
.It Cm oxtabs Pq Fl oxtabs
Expand (do not expand) tabs to spaces on output.
.\" .It Cm tab0 tab3
.\" Select tab epxansion policy.
.\" .Cm tab0
.\" disables tab expansion, while
.\" .Cm tab3
.\" enables it.
.It Cm tab0 tab1 tab2 tab3
Select the style of delay for horizontal tabs (e.g., set TABDLY to TAB0).
.It Cm tabs Pq Fl tabs
Same as
.Cm tab0
.Cm ( tab3 ) .
.It Cm vt0 vt1
Select the style of delay for vertical tabs (e.g., set VTDLY to VT0).
.El
.Ss Local Modes:
Local mode flags (lflags) affect various and sundry characteristics of terminal
processing.
Historically the term "local" pertained to new job control features
implemented by Jim Kulp on a
.Tn Pdp 11/70
at
.Tn IIASA .
.\" Later the driver ran on the first
Later, the driver ran on the first
.Tn VAX
at Evans Hall, UC Berkeley, where the job control details
.\" were greatly modified but the structure definitions and names
.\" remained essentially unchange.
were greatly modified,
but the structure definitions and names remained essentially unchanged.
The second interpretation of the 'l' in lflag
.\" is ``line discipline flag'' which corresponds to the
is ``line discipline flag'', which corresponds to the
.Ar c_lflag
of the
.Ar termios
structure.
.Bl -tag -width Fl
.It Cm altwerase Pq Fl altwerase
Use (do not use) an alternate word erase algorithm when processing
.Dv WERASE
characters.
This alternate algorithm considers sequences of
alphanumeric/underscores as words.
It also skips the first preceding character in its classification
(as a convenience, since the one preceding character could have been
erased with simply an
.Dv ERASE
character.)
.It Cm echo Pq Fl echo
Echo back (do not echo back) every
character typed.
.It Cm echoctl Pq Fl echoctl
If
.Cm echoctl
is set, echo control characters as ^X.
Otherwise, control characters
echo as themselves.
.It Cm echoe Pq Fl echoe
The
.Dv ERASE
character shall (shall not) visually erase the last character
in the current line from the display, if possible.
.It Cm echok Pq Fl echok
Echo (do not echo)
.Dv NL
after
.Dv KILL
character.
.It Cm echoke Pq Fl echoke
The
.Dv KILL
character shall (shall
not) visually erase the
current line from the
display, if possible.
.It Cm echonl Pq Fl echonl
Echo (do not echo)
.Dv NL ,
even if echo is disabled.
.It Cm echoprt Pq Fl echoprt
For printing terminals.
If set, echo erased characters backwards within ``\\''
and ``/''.
Otherwise, disable this feature.
.It Cm flusho Pq Fl flusho
Indicates output is (is not) being discarded.
.It Cm icanon Pq Fl icanon
Enable (disable) canonical input
.Pf ( Dv ERASE
and
.Dv KILL
processing).
.It Cm iexten Pq Fl iexten
Enable (disable) any implementation-defined special control characters
that are not currently controlled by
.Cm icanon ,
.Cm isig ,
.Cm ixoff ,
or
.Cm ixon .
.It Cm isig Pq Fl isig
Enable (disable) the checking of characters
against the special control characters
.Dv INTR , QUIT ,
and
.Dv SUSP .
.It Cm mdmbuf Pq Fl mdmbuf
If set, flow control output based on condition of Carrier Detect.
Otherwise, writes return an error if Carrier Detect is low
(and Carrier is not being ignored with the
.Dv CLOCAL
flag.)
.It Cm noflsh Pq Fl noflsh
Disable (enable) flush after
.Dv INTR , QUIT ,
or
.Dv SUSP .
.It Cm pendin Pq Fl pendin
Indicates input is (is not) pending
after a switch from non-canonical to canonical mode
and will be re-input when a read becomes pending or more input arrives.
.It Cm tostop Pq Fl tostop
Send (do not send)
.Dv SIGTTOU
for background output.
This causes background jobs to stop if they attempt
terminal output.
.El
.Ss Control Characters:
.Bl -tag -width Fl
.It Ar control-character Ar string
Set
.Ar control-character
to
.Ar string .
If string is a single character,
the control character is set to
that character.
If string is the
two character sequence "^-" or the
string "undef" the control character
is disabled (i.e., set to
.Pf { Dv _POSIX_VDISABLE Ns } . )
.Pp
Recognized control-characters:
.Bd -ragged -offset indent
.Bl -column character Subscript
.It control- Ta \& Ta \&
.It character Ta Subscript Ta Description
.It _________ Ta _________ Ta _______________
.It eof Ta Tn VEOF Ta EOF No character
.It eol Ta Tn VEOL Ta EOL No character
.It eol2 Ta Tn VEOL2 Ta EOL2 No character
.It erase Ta Tn VERASE Ta ERASE No character
.It erase2 Ta Tn VERASE2 Ta ERASE2 No character
.It werase Ta Tn VWERASE Ta WERASE No character
.It intr Ta Tn VINTR Ta INTR No character
.It kill Ta Tn VKILL Ta KILL No character
.It quit Ta Tn VQUIT Ta QUIT No character
.It susp Ta Tn VSUSP Ta SUSP No character
.It start Ta Tn VSTART Ta START No character
.It stop Ta Tn VSTOP Ta STOP No character
.It dsusp Ta Tn VDSUSP Ta DSUSP No character
.It lnext Ta Tn VLNEXT Ta LNEXT No character
.It reprint Ta Tn VREPRINT Ta REPRINT No character
.It status Ta Tn VSTATUS Ta STATUS No character
.El
.Ed
.It Cm min Ar number
.It Cm time Ar number
Set the value of min or time to
number.
.Dv MIN
and
.Dv TIME
are used in Non-Canonical mode input processing (-icanon).
.El
.Ss Combination Modes:
.Bl -tag -width Fl
.It Ar saved settings
Set the current terminal
characteristics to the saved settings
produced by the
.Fl g
option.
.It Cm cols Ar number
Same as
.Cm columns .
.It Cm columns Ar number
The terminal size is recorded as having
.Ar number
columns.
.It Cm crt Pq Fl crt
Set (disable) all modes suitable for a CRT display device.
.It Cm dec
Set modes suitable for users of Digital Equipment Corporation systems
.Dv ( ERASE ,
.Dv KILL ,
and
.Dv INTR
characters are set to ^?, ^U, and ^C;
.Dv ixany
is disabled, and
.Dv crt
is enabled.)
.It Cm ek
Reset
.Dv ERASE ,
.Dv ERASE2 ,
and
.Dv KILL
characters
back to system defaults.
.It Fl  evenp
Same as
.Fl oddp
and
.Fl parity .
.It Cm evenp
Enable
.Cm parenb
and
.Cm cs7 ;
disable
.Cm parodd .
.It Cm extproc Pq Fl extproc
If set, this flag indicates that some amount of terminal processing
is being performed by either the terminal hardware
or by the remote side connected to a pty.
.It Cm kerninfo Pq Fl kerninfo
Enable (disable) the system generated status line associated with
processing a
.Dv STATUS
character (usually set to ^T).
The status line consists of the
system load average, the current command name, its process ID, the
event the process is waiting on (or the status of the process), the user
and system times, percent cpu, and current memory usage.
.\" .Pp
.\" If the
.\" .Xr sysctl 8
.\" variable
.\" .Va kern.tty_info_kstacks
.\" is set to a non-zero value, the status message also includes the kernel program
.\" stack of the foreground thread.
.It Cm \&nl Pq Fl \&nl
Enable (disable)
.Cm icrnl .
In addition,
.Fl nl
unsets
.Cm inlcr
and
.Cm igncr .
.It Fl  oddp
Same as
.Fl evenp
and
.Fl parity .
.It Cm oddp
Enable
.Cm parenb ,
.Cm cs7 ,
and
.Cm parodd .
.It Fl parity
Disable
.Cm parenb ;
set
.Cm cs8 .
.It Cm parity
Same as
.Cm evenp .
.It Cm raw Pq Fl raw
If set, change the modes of the terminal so that no input or output processing
is performed.
If unset, change the modes of the terminal to some reasonable
state that performs input and output processing.
Note that since the
terminal driver no longer has a single
.Dv RAW
bit, it is not possible to intuit what flags were set prior to setting
.Cm raw .
This means that unsetting
.Cm raw
may not put back all the setting that were previously in effect.
To set the terminal into a raw state and then accurately restore it,
the following shell code is recommended:
.Bd -literal
save_state=$(stty -g)
stty raw
\&...
stty "$save_state"
.Ed
.It Cm rows Ar number
The terminal size is recorded as having
.Ar number
rows.
.It Cm sane
Resets all modes to reasonable values for interactive terminal use.
.It Cm size
The size of the terminal is printed as two numbers on a single line,
first rows, then columns.
.It Cm tty
Set the line discipline to the standard terminal line discipline
.Dv TTYDISC .
.El
.Ss Compatibility Modes:
These modes remain for compatibility with the previous version of
the
.Nm
command.
.Bl -tag -width Fl
.It Cm all
Reports all the terminal modes as with
.Cm stty Fl a
except that the control characters are printed in a columnar format.
.It Cm brk Ar value
Same as the control character
.Cm eol .
.It Cm cbreak
If set, enables
.Cm brkint , ixon , imaxbel , opost , isig , iexten ,
and
.Fl icanon .
If unset, same as
.Cm sane .
.It Cm cooked
Same as
.Cm sane .
.It Cm crtbs Pq Fl crtbs
Same as
.Cm echoe .
.It Cm crterase Pq Fl crterase
Same as
.Cm echoe .
.It Cm crtkill Pq Fl crtkill
Same as
.Cm echoke .
.It Cm ctlecho Pq Fl ctlecho
Same as
.Cm echoctl .
.It Cm decctlq Pq Fl decctlq
The converse of
.Cm ixany .
.It Cm everything
Same as
.Cm all .
.It Cm flush Ar value
Same as the control character
.Cm discard .
.It Cm litout Pq Fl litout
The converse of
.Cm opost .
.It Cm new
Same as
.Cm tty .
.It Cm newcrt Pq Fl newcrt
Same as
.Cm crt .
.It Cm old
Same as
.Cm tty .
.It Cm oxtabs Pq Fl oxtabs
Expand(do not expand) tabs to spaces on output.
.It Cm pass8
The converse of
.Cm parity .
.It Cm prterase Pq Fl prterase
Same as
.Cm echoprt .
.It Cm rprnt Ar value
Same as the control character
.Cm reprint .
.It Cm tabs Pq Fl tabs
The converse of
.Cm oxtabs .
.It Cm tandem Pq Fl tandem
Same as
.Cm ixoff .
.El
.Sh EXIT STATUS
.Ex -std
.Sh LEGACY DESCRIPTION
In legacy operation, the
.Cm bs[01] ,
.Cm cr[0-3] ,
.Cm ff[01] ,
.Cm nl[01] ,
.Cm tab[0-3] ,
and
.Cm vt[01]
control modes are not accepted, nor are
.Cm ocrnl Pq Fl ocrnl ,
.Cm ofdel Pq Fl ofdel ,
.Cm ofill Pq Fl ofill ,
.Cm onlret Pq Fl onlret ,
and
.Cm onocr Pq Fl onocr .
.Pp
For more information about legacy mode, see
.Xr compat 5 .
.Sh SEE ALSO
.\" .Xr resizewin 1 ,
.Xr termios 4 ,
.Xr compat 5
.\" .Xr pstat 8
.Sh STANDARDS
The
.Nm
utility is expected to be
.St -p1003.2
compatible.
The flags
.Fl e
and
.Fl f
are
extensions to the standard.
.Sh HISTORY
A
.Nm
command appeared in
.At v2 .
